Modeling critical habitat breadth for Gopherus tortoises

The A.P.E. lab is leading a large, multi-institution collaboration investigating the climate resilience of populations of gopher tortoise (Gopherus polyphemus) and Mojave desert tortoise (Gopherus agassizii). In this project, funded by the Department of Defense (SERDP program), we are building models of tortoise vital rates (age-structured survival, fecundity) as functions of environmental and climatic covariates and simultaneously assessing for evidence of local behavioral and physiological adaptations. We are then using these models to quantify the range of environmental change that populations can withstand in situ without the need for natural selection or long-distance movement to more suitable habitats.

Here is a visual schematic of our study design:

And below is a big-picture schematic of our project:

UNR:
* Ken Nussear
* Marjorie Matocq

USGS:
* Todd Esque

Stony Brook University:
* Resit Akcakaya

Publications

• Loope, K., Walden, M.A., Shoemaker, K.T., Hunter, E.A. In prep. Sex determination of hatchling Gopherus tortoises. Journal of Herpetology.
• Mitchell, C., Friend, D., Hunter, E.A., Nussear, K.E., Phillips, L., Shoemaker, K.T. In prep. Effects of climate on desert tortoise fecundity. Biological Conservation.
• Walden, M.A., Hunter, E.A., Devan-Song, A., Shoemaker, K.T., In prep. Techniques and challenges in measuring fat reserves in desert tortoises. Journal of Zoo and Wildlife Medicine.
• Hunter, E.A, Walden, M.A., Shoemaker, K.T. In prep. Sensitivity of gopher tortoise population vital rates to climatic gradients. Biological Conservation.
• Shoemaker, K.T., Hunter, E.A., Walden, M.A., Nussear, K.E., Esque, T.C. In prep. Spatio-temporal drivers of Mojave Desert Tortoise demography and movements. Ecography.
• Hunter, E.A., and Rostal, D.C. In review. Effects of fire management on gopher tortoise population dynamics depend on habitat context. Journal of Wildlife Management.